The magnetic cards which comprise a substrate of a thermoplastic resin and a magnetic recording layer provided thereon at a given width and in a given direction, and in a given area of which the desired matters such as letters and figures can be formed by an embossing process, have been widely used as credit cards, cash cards for banking, identification cards, cards for oil filling, cards for shopping and others.
These conventional magnetic cards comprise a thermoplastic resin sheet of polyvinyl chloride or the like as a substrate and a magnetic recording layer which is called magnetic stripes and formed by heat-transferring or bonding a magnetic layer formed on a PET (polyethylene terephthalate) tape or the like, to the desired portion of the substrate in the form of stripes.
The constitution of these magnetic cards is schematically shown in FIG. 1 and FIG. 2.
FIG. 1 shows a conventional magnetic card, The magnetic card 10 comprises substrates 21 and 22 of polyvinyl chloride sheets printed with letters or designs 41 and 42, protective layers 34 of transparent polyvinyl chloride sheets through which the letters or designs 41 and 42 can be seen, magnetic stripe 31 heat-transferred or bonded to the protective layer 34 and letters and FIGS. 43 and 44 formed by embossing treatment.
In this constitution, the portion to be printed with letters or designs 41 is limited by the magnetic stripe 31 and therefore the degree of freedom for designs is restricted. Thus, high level of designs are hindered.
Recently, for enhancement of the degree of freedom for designing, such magnetic card 10 as shown in FIG. 2 has been increasingly used. That is, in the magnetic card 10 hiding layer 32 is provided on the whole surface of substrate 23 to which magnetic stripe 31 has been transferred, then the letters or designs 41 are printed on this hiding layer 32 and the printed letters or designs are protected with protective layer 33.
However, formation of the hiding layer 32 which hides the magnetic stripe 31 requires a special technique for hiding the difference in level or in color tone between the magnetic stripe 31 and the substrate 23 of a transparent polyvinyl chloride sheet to which the stripe 31 has been transferred or bonded. As a result, improvement of productivity has been inhibited.
Furthermore, the magnetic stripe 31 is relatively expensive, registration in transferring or bonding of the stripe and registration in cutting of the cards are difficult to cause reduction in the yield. Thus, improvements in material cost and production cost have also been desired.
As an approach to solve the above problems and to provide magnetic cards which are inexpensive and stable in quality and a process for production thereof, it has been proposed to form, in succession, a magnetic recording layer, a hiding layer and a design layer on the whole surface of the substrate of a magnetic card (See Japanese Patent Kokai (Laid-Open) Nos. Sho 48-23337 and 54-73608 and Hei 2-249696). The proposed magnetic cards can solve the problems in material cost and production cost, but they still suffer from the problems that when the desired matters such as letters and figures are formed in a given position of the magnetic cards by embossing treatment, there occur cracking, peeling and exfoliation of the magnetic film in the portions subjected to the embossing treatment to expose the substrate and thus, the appearance is seriously damaged and commercial value is diminished.